The present invention relates to a turbine housing of a turbocharger of the type in which a passage through which exhaust gases are charged into a turbine is partitioned into a plurality of paths.
A typical conventional turbine housing with a construction as shown in FIGS. 5 and 6 has a turbine housing main body 1 and a partition wall 4 formed integral therewith so that thermal stresses produced in the partition wall 4 become excessive and cracks tend to propagate from the leading end of the partition wall 4 due to the thermal fatigue and consequently the partition wall 4 is broken, losing its function. Especially when the exhaust gases do not flow through a plurality of scrolls simultaneously, the temperature difference between them becomes so high that the service life of the partition wall 4 is considerably shortened.
In order to overcome the above-described problem, there has been proposed an improved divided-type turbine housing as shown in FIG. 7 in which an independent partition wall 4 is joined to a turbine housing main body 1 so as to decrease thermal stresses produced. The turbine housing main body less restricts the thermal deformations of the partition wall 4 so that the life of the partition wall 4 can be prolonged.
However, in the turbine housing of the type shown in FIG. 7, the partition wall 4 is loosely fitted into mated engaging grooves on the turbine housing main body 1 so that the freedom of thermal deformation is enhanced. As a result, due to thermal influences, the partition wall 4 deforms itself in the radial direction and simultaneously contracts or expands in the peripheral or circumferential direction. Therefore, as shown in FIG. 8, when the wound end which less influences the performance of the partition wall 4 is terminated into a fixed portion 3, the position of the partition wall 4 at the gas inlet may vary, leaving a space .DELTA.l. As a result, there results a problem that the exhaust gases may be mixed at the flange portion in the gas inlet. Furthermore, there arises a problem that the end of the partition wall 4 may extend beyond the flange surface, causing the deformations of the partition wall or damaging a gasket at the gas inlet. Similar problems are observed in the turbine housing of the type in which the wound end of the partition wall is not separated because the thermal expansion corresponding to the length of the partition wall occurs at the gas inlet.
In view of the above, one of the objects of the present invention is to prevent the mixture of exhaust gases at the flange portion in the gas inlet.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of a preferred embodiment thereof taken in conjunction with the accompanying drawings.